1. Field of the Invention
The invention relates in general to a transformer, and more particularly to a miniaturized transformer.
2. Description of the Related Art
As the technology develops, the trends of all kinds of electronic devices have been directed toward miniaturization and light weight. Internal electronic devices also develop toward miniaturization. However, many problems occur in the process of miniaturizing electronic devices.
Take transformers as an example. It has been over a century since transformers were first manufactured by a Hungarian company called GANZ in 1885. Transformers are widely used for a long time and have evolved into many types of transformers. However, the principles are still unchanged. Transformers transfer electrical energy to/from magnetic energy. Two sets of coils are wound on a common iron core. The coil connected to a power terminal is called primary coil, and the coil connected to a load terminal is called secondary coil. Or, the coils can also be called as high voltage coil and low voltage coil based on the voltage magnitude. The primary coil can be the high voltage coil or the low voltage coil depending on the voltage magnitude.
When the primary coil is connected to an alternating current power source, the current passing through the coil generates a change in the magnetic flux. The secondary coil at the other end generates alternating current with the same frequency due to induced electromotive force (EMF).
However, the distance between the primary coil and the secondary coil (or called the high voltage coil and the low voltage coil) is enlarged to increase the leakage inductance of the transformer, which increases the size of the transformer as well. Therefore, the requirement of miniaturization cannot be met. When the diameter of the primary coil or the secondary coil (or called the high voltage coil and the low voltage coil) is reduced, the distance between the primary coil and the secondary coil is enlarged. However, the current limit is lowered, which endangers the safety of using transformers.
Therefore, it is still a critical difficulty to develop miniaturized transformers with high leakage inductance.